Environmental Chemistry JEE Main previous year questions with solutions

5 solved JEE Main questions on Environmental Chemistry, free to read — no sign-in needed. The full chapter has 113 questions; sign in to attempt the remaining 108 in the exam simulator.

1. Q1JEE Main 2023 (15 Apr, Shift 1)
   The possibility of photochemical smog formation will be minimum at
   1. A.Srinagar, Jammu and Kashmir in January
   2. B.Kolkata in October
   3. C.Mumbai in May
   4. D.New-Delhi in August (Summer)
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   Answer: (A)

   Photochemical smog is a mixture of pollutants that are formed when nitrogen oxides and volatile organic compounds (VOCs) react to sunlight, creating a brown haze above cities. It tends to occur more often in summer, because that is when we have the most sunlight. The average temperature of Kashmir in January is estimated to be $-3.6^{\circ}C$ in Srinagar, $-11.8^{\circ}C$ in Pahalgam, and $-10.4^{\circ}C$ in Gulmarg as their minimum temperatures.
2. Q2JEE Main 2023 (13 Apr, Shift 2)
   Which of the following are the Green house gases? A. Water vapour B.Ozone C.${I}_{2}$ D.Molecular hydrogen Choose the most appropriate answer from the options given below :
   1. A.A and D only
   2. B.B and C only
   3. C.A and B only
   4. D.C and D only
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   Answer: (C)

   The greenhouse effect is a process that occurs when gases in Earth's atmosphere trap the Sun's heat. This process makes Earth much warmer than it would be without an atmosphere. The main greenhouse gases whose concentrations are rising are carbon dioxide, methane, nitrous oxide, hydrochlorofluorocarbons (HCFCs), hydrofluorocarbons (HFCs) and ozone in the lower atmosphere. ${I}_{2}$ and ${H}_{2}$ are not green house gases.
3. Q3JEE Main 2023 (13 Apr, Shift 1)
   The radical which mainly causes ozone depletion in the presence of $UV$ radiations is :
   1. A.${Cl}^{\cdot }$
   2. B.${NO}^{\cdot }$
   3. C.$O^{\cdot }H$
   4. D.${CH}_{3}^{\cdot }$
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   Answer: (A)

   Chlorofluorocarbons are chemicals which contain carbon, chlorine and fluorine. Ozone layer breaks when these CFC's are released into the atmosphere.So. Chlorine is one of the radical which belongs to CFC's family, responsible for break down.
4. Q4JEE Main 2023 (11 Apr, Shift 2)
   Which of the following compounds is an example of Freon?
   1. A.${C}_{2}{H}_{2}{F}_{2}$
   2. B.${C}_{2}{F}_{4}$
   3. C.${C}_{2}{HF}_{3}$
   4. D.${C}_{2}{Cl}_{2}{F}_{2}$
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   Answer: (D)

   ${C}_{2}{Cl}_{2}​{F}_{2}$​ is an example of freon. It can act as an aerosol propellant, refrigerant, or organic solvent because it is a gas at room temperature and a liquid when cooled or compressed. Freon is a term that was commonly used to refer to a group of chlorofluorocarbon (CFC) and hydrochlorofluorocarbon (HCFC) compounds.
5. Q5JEE Main 2023 (11 Apr, Shift 1)
   Given below are two statements : Statement-I : If BOD is $4ppm$ and dissolved oxygen is $8ppm$ , then it is a good quality water. Statement-II : If the concentration of zinc and nitrate salts are $5ppm$ each, then it can be a good quality water. In the light of the above statements, choose the most appropriate answer from the options given below :
   1. A.Statement I is correct but Statement II is incorrect
   2. B.Statement I is incorrect but Statement II is correct
   3. C.Both the statements I and II are incorrect
   4. D.Both the statements I and II are correct
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   Answer: (D)

   Drinking water has a $BOD$ level of $1-2ppm$. When the $BOD$ value of water is in the range $3-5ppm$, the water is moderately clean. Polluted water has a $BOD$ value in the range of $6-9ppm$. Healthy water should generally have dissolved oxygen concentrations above $6.5-8mg/L$ Drinking water with concentrations of nitrate (measured as nitrate-nitrogen) below $10mg$ of nitrate per liter of water ($mg/L$) is considered safe. Permissible limit of $Zn$ in potable water is $5ppm$.